Simplify and comment the translation between
registers and struct tm.
Signed-off-by: Michael Davidsaver <mdavidsa...@gmail.com>
---
hw/timer/ds1338.c | 35 +++++++++++++++++------------------
1 file changed, 17 insertions(+), 18 deletions(-)
diff --git a/hw/timer/ds1338.c b/hw/timer/ds1338.c
index 72a4692d60..9bcda26e51 100644
--- a/hw/timer/ds1338.c
+++ b/hw/timer/ds1338.c
@@ -88,23 +88,23 @@ static void capture_current_time(DS1338State *s)
* which will be actually read by the data transfer operation.
*/
struct tm now;
+ bool mode12 = ARRAY_FIELD_EX32(s->nvram, HOUR, SET12);
qemu_get_timedate(&now, s->offset);
+
s->nvram[R_SEC] = to_bcd(now.tm_sec);
s->nvram[R_MIN] = to_bcd(now.tm_min);
- if (ARRAY_FIELD_EX32(s->nvram, HOUR, SET12)) {
- int tmp = now.tm_hour;
- if (tmp % 12 == 0) {
- tmp += 12;
- }
- s->nvram[R_HOUR] = 0;
+ s->nvram[R_HOUR] = 0;
+ if (mode12) {
+ /* map 0-23 to 1-12 am/pm */
ARRAY_FIELD_DP32(s->nvram, HOUR, SET12, 1);
- if (tmp <= 12) {
- ARRAY_FIELD_DP32(s->nvram, HOUR, AMPM, 0);
- ARRAY_FIELD_DP32(s->nvram, HOUR, HOUR12, to_bcd(tmp));
- } else {
- ARRAY_FIELD_DP32(s->nvram, HOUR, AMPM, 1);
- ARRAY_FIELD_DP32(s->nvram, HOUR, HOUR12, to_bcd(tmp - 12));
+ ARRAY_FIELD_DP32(s->nvram, HOUR, AMPM, now.tm_hour >= 12u);
+ now.tm_hour %= 12u; /* wrap 0-23 to 0-11 */
+ if (now.tm_hour == 0u) {
+ /* midnight/noon stored as 12 */
+ now.tm_hour = 12u;
}
+ ARRAY_FIELD_DP32(s->nvram, HOUR, HOUR12, to_bcd(now.tm_hour));
+
} else {
ARRAY_FIELD_DP32(s->nvram, HOUR, HOUR24, to_bcd(now.tm_hour));
}
@@ -182,14 +182,13 @@ static int ds1338_send(I2CSlave *i2c, uint8_t data)
break;
case R_HOUR:
if (FIELD_EX32(data, HOUR, SET12)) {
- int tmp = from_bcd(FIELD_EX32(data, HOUR, HOUR12));
+ /* 12 hour (1-12) */
+ /* read and wrap 1-12 -> 0-11 */
+ now.tm_hour = from_bcd(FIELD_EX32(data, HOUR, HOUR12)) % 12u;
if (FIELD_EX32(data, HOUR, AMPM)) {
- tmp += 12;
+ now.tm_hour += 12;
}
- if (tmp % 12 == 0) {
- tmp -= 12;
- }
- now.tm_hour = tmp;
+
} else {
now.tm_hour = from_bcd(FIELD_EX32(data, HOUR, HOUR24));
}
--
2.11.0
